Help with a simple addition query

[snypa]

I want to create a query that will add the values from two rows. The two rows have two attributes that are the same

The table is as follows

ID InvNumber ItemNumber PaymentNo Amount
1 W123 1 1 100
1 W123 2 1 100


I want to add the amounts and the selection criteria to be based on the InvNumber and Payment No. I am using the Access
GUI to write the query and how can I just add the two amounts simply??

Thank you in advance

 

[cjard]

SELECT id, invnumber, paymentnumber, SUM(amount) FROM table GROUP BY id, invnumber, paymentnumber